May; might

Uses

Present/Future

Past

1) polite request

May I borrow your pen? Might I borrow your pen?

—

2) formal permission

You may leave the room.



3) less than 50% certainty

— Where is John? He may be at the library. He might be at the library.

He may have been at the library. He might have been at the library.

Uses

Present/Future

Past

1) duty; obligation; strong necessity

I must go to class today. I have to go to class today. I have got to go to class today.

I had to go to class yesterday.

2) lack of necessity (negative)

I don't have to go to class today.

I didn't have to go to class yesterday.

3) prohibition (negative)

You must not open that door.



4) 90% certainty

Mary isn't in class. She must be sick. (present only)

Mary must have been sick yesterday.

5) plan; agreement

We are to meet at nine.

We were to meet at nine.

6) order; instruction

You must go there at once. You are to go there at once.



7) destiny (past only)



He was never to see his wife again.

Uses

Present/Future

Past

1) advisability; desirability

I should study tonight. I ought to study tonight.

I should have studied last night. I ought to have studied last night.

2) 90% certainty

She should do well on the test. She ought to do well on the test. (future only)

She should have done well on the test. She ought to have done well on the test.

Uses

Present/Future

Past

1) polite question to make a suggestion

Shall I open the window?



2) future with «I» or «we» as subject

I shall arrive at nine. (will = more common)



Uses

Present/Future

Past

1) 100 % certainty

He will be here at nine.

He said he would be here at nine.

2) polite request

Will you please pass the salt?

Would you please pass

the salt?

Would you mind if I left early?



3) willingness

— The phone's ringing.

I'll get it.



4) preference

I would rather go to the park than stay home.

I would rather have gone to the park.